Remote Display port is not saved when it is zero

The GUI at the remote display settings say: You can set the remote display port to 0 (zero) if you want to specify the default RDP port.
But when you do that, and close the settings window, the configuration is not saved.
Suggestions:

Save 0 as 3389

Save 0 as default

Make it possible for the GUI/backend to differentiate between 0, , null etc.